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[SKOS] ISSUE-39A Grouping for Mapping? (was RE: [SKOS] A new proposal for ISSUE-39 ConceptualMappingLinks)

From: Miles, AJ \(Alistair\) <A.J.Miles@rl.ac.uk>
Date: Tue, 4 Dec 2007 18:40:44 -0000
Message-ID: <677CE4DD24B12C4B9FA138534E29FB1D03B3F7C8@exchange11.fed.cclrc.ac.uk>
To: "Miles, AJ \(Alistair\)" <A.J.Miles@rl.ac.uk>, "Antoine Isaac" <aisaac@few.vu.nl>, <public-swd-wg@w3.org>
Cc: <public-esw-thes@w3.org>, <public-swd-wg@w3.org>

Hi all,

> (ISSUE-39A) Should "grouping" constructs for mapping be 
> included, and if so, what are their semantics?

My position: I do not think it's a good idea to include any "grouping" constructs such as "AND", "OR", "NOT" in the SKOS recommendation, because it would require substantial additions to the theoretical foundation of SKOS.

The SKOS Mapping vocabulary was originally defined in two documents, [1] and [2]. Both of these include "AND", "OR" and "NOT" constructs. There are some conflicts between [1] and [2], but both share the basic idea that "AND", "OR" and "NOT" are "groups" of concepts. 

How are these to be interpreted? Again, there are some conflicts between [1] and [2]. [1] talks about set operations (intersection, union, complement, see [1]#AND, [1]#OR, [1]#NOT). [2] talks about set operations too (see [2]#3.a), however [2] also talks about "intension", e.g. "Use the AND construct to create a mapping target that represents the common intension of two or more concepts."

There are difficulties with the set-based interpretation of "AND", "OR", and "NOT". 

Firstly, to give a proper account of this interpretation, you need a notion of a "query" which can be evaluated with respect to an "index". 

If you have both of these, mapping statements involving "AND", "OR" and "NOT" constructs can make sense as mappings between *query expressions*. Mappings between composite query expressions can be given a purely operational interpretation, which defines procedures for translating either indexes or query expressions. See [3], chapter 7.

This is the only way I know of providing a solid foundation for "AND", "OR" and "NOT" expressions. To introduce this foundation for SKOS, we would first need to establish a notion of a "query", which is no small task.

For these reasons, at the moment I would vote against including "AND", "OR" or "NOT" grouping constructs in the SKOS recommendation.

However, I wouldn't rule out a notion of "coordination". I think "coordination" can be given an informal explanation, for which there is some precedent.

Anyway, that's all I have for now, cheers,

Alistair.

[1] <http://www.w3.org/2004/02/skos/mapping/spec/2004-11-11.html>
[2] <http://www.w3c.rl.ac.uk/SWAD/deliverables/8.4.html>
[3] <http://purl.org/net/retrieval>

--
Alistair Miles
Research Associate
Science and Technology Facilities Council
Rutherford Appleton Laboratory
Harwell Science and Innovation Campus
Didcot
Oxfordshire OX11 0QX
United Kingdom
Web: http://purl.org/net/aliman
Email: a.j.miles@rl.ac.uk
Tel: +44 (0)1235 445440  
Received on Tuesday, 4 December 2007 18:41:05 GMT

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